Research Of Nitrides-Oxides-Carbon Composite Prepared And Bonding Mechanism By High-temperature Nitriding

Carbon containing refractories?Al₂O₃-C and MgO-C refractories?have been widely used in steelmaking and other high-temperature field.However,the internal of carbon containing refractories can not form a relatively effective chemical bonding,which affect the mechanical performance of the materials.Sialon-Al₂O₃-C?SAC?and Si₃N₄-MgO-C?SMC?are prepared by a method of in-situ nitriding at elevated temperatures,which exhibiting excellent properties.And the formation of chemical bonding between oxides and nitrides,nitrides and graphite are achieved.And the bonding mode between the different phases of the materials are studied.In this paper,effects of silicon powder content on phase composition,microstructure and properties of SAC and SMC materials are first discussed.Second,the interfacial bonding between oxide and nitride,nitride and graphite are studied in SAC and SMC materials;and effects of matrix on the interfacial bonding of SAC and SMC materials are also studied.The last,The bonding mode between the different phases of SAC and SMC materials are studied by X-ray photoelectron spectroscopy?XPS?,which provide the theoretical basis for the bonding of nitrides-oxides-carbon refractories.?1?.Effects of silicon powder content on the properties of SAC and SMC materials are investigated.When the content of silicon powder is 10wt%in SAC material,the sizes of?-Sialon crystal are the largest,the cold crushing strength?CCS?is higher,and the overall performance is better.In SMC material,the sizes of?-Si₃N₄ crystal increase first and then decrease when the content of silicon powder increase.The cold crushing strength?CCS?is higher,and the overall performance is better,when the content of silicon powder is 16wt%in SMC material.?2?.The interfacial bonding of SAC and SMC materials are observed by TEM and HRTEM.The interfaces bonding among?-Sialon and Al₂O₃,?-Sialon and graphite can be formed in SAC material.The interfaces bonding among?-Si₃N₄ and MgO,?-Si₃N₄and graphite can be formed in SMC material.In addition,the formation of matrix affect the interface bonding of the SAC and SMC materials.?3?.The bonding of Al-O,Al-Al,Si-Si,Si-N,Si-O,C-C,C-Si,N-Si,N-O,O-O,O-Al and O-Si form in prepared SAC material by using XPS analysis.The bonding of Mg-O,Mg-Si,Si-Si,Si-C,Si-N,Si-O,C-C,C-Si,C-N,N-Si,N-N,O-O,O-Mg and O-Si form in prepared SMC material.The formation of matrix have little effect on the bonding within the material.